Gen 6 seems a little too early to announce so it's either, gen 3 remake, new stadium game for Wii-U, or (hopefully) a new Pokemon Snap for 3DS.
Well.. if you're using that as an example of an impossibility it'd be slightly wrong, Eiji Aonuma himself acknowledged the fact people want a MM remake, and basically said it's possible after a new 3DS Zelda title.
Ugh... I know it's coming, but I'm just hoping the nostalgia "fans" don't have to shove "GLORIOUS 151 MASTER RACE" shit down everyone else's throat in every single Pokemon thread in existence.